This invention relates to a process for manufacturing a textured yarn from a continuous multi-filament yarn of artificial fiber, where the individual component filaments are aligned substantially parallel to the longitudinal axis of the yarn with complicated loops and entaglements and entwined by genuine twists to form a structure resembling a spun yarn in appearance, texture and handling. This invention furthermore relates to a process for manufacturing a core yarn having a core thread enveloped in a sheath of a textured yarn as just described to give the appearance, texture, and handling resembling a spun yarn.
A typical method for manufacturing a yarn of this type is disclosed in the specification of British Pat. No. 1,082,401 wherein a single freshly formed continuous filament is extruded through an orifice in a spinneret at room temperature and, after cooling and solidification, is wrapped around the surface of a truncated cone under the guidance of a traverse mechanism which is located in a short distance above the cone surface. As a result of the reciprocating movement imparted to the filament, it is wound back and forth across the surface of the conical godet as a series of interconnected helicies, which accumulate thereon in the form of a tapered sleeve. The sleeve while being propagated by the wrapping of the continuously advancing filament is progressively pulled down in the inclined surface of the godet in the direction of its axis of rotation by means of a conventional winding arrangement.
The inventors of British Pat. No. 1,082,401 have proposed another method in British patent specification No. 1,102,095, wherein a continuous filament is wrapped around the surface of a truncated cone in the same manner as in British Pat. No. 1,082,401 just discussed, the truncated cone having an axially extending passage. Through the reciprocating movement imparted to the filament, the filament is wound around the surface of the conical godet as a series of interconnected helicies, which accumulates thereon in the form of a tapered sleeve. The sleeve while being propagated by the wrapping of the continually advancing filament is progressively pulled down the inclined surface of the godet in the direction of its axis of rotation. At the converging end of the conical godet, the sleeve is pulled in a reverse direction through the axially extending passage in the godet, everting the sleeve, and transferring the relatively short loops which project outward from the main mass of the sleeve from the periphery to the interior.
British patent specification No. 1,158,602 describes the production of a core yarn which applies the methods disclosed in the afore-discussed British patent specification Nos. 1,082,401 and 1,102,095, wherein an additional yarn is supplied as a core strand to the forward end of the godet to join a sleeve which is continuously withdrawn and collected as a core yarn with a composite structure.
The core yarn so obtained has a centrally disposed core thread and a wrapping component constituted by one or more continuous filaments in the form of serially-connected, essentially axially extending loops arranged so that they progressively advance along the axis and helically twist around and completely envelop the core strand.
In any of the prior-art methods described above, a freshly spun continuous yarn is passed to the surface of a conical godet around which the filament is wound under the guidance of a high-speed traverse mechanism. Currently known high-speed traverse mechanisms have complicated structures and are difficult to maintain. Furthermore, they have upper limits to their reciprocating speed, which in turn place limits on the utility of the three methods. If the peripheral surface of a godet is increased without an accompanying increase in the reciprocating movement, for instance, the angle at which filaments lie in relation to each other on the godet surface as well as entanglements among the filaments will decrease and withdrawal of the sleeve will become more difficult and the irregularity of the yarn will increase.
In these prior-art methods, furthermore, the ratio of the peripheral speed of the godet to the speed of sleeve withdrawal, or the doubling number must be quite large, that is, approximately 100 or over, in order to maintain sufficient twists in the yarn. Therefore, a continuous filament which is supplied to the godet must have a thickness on the order of approximately one-hundredth of that of the yarn to be collected, imposing a limitation on the productivity of such a filament and pushing up the cost of the same. In the conventional methods, the freshly formed continuous filament is passed directly to a rapidly rotating godet with such an economic factor in mind. Nevertheless, the arrangement does not overcome the basic drawback that the productivity of the method of manufacture of such a continuous filament is low.
It is also well known in the art that the continuous filament in the conventional methods usually undergoes insufficient drafting and thus has low strength, excess ductility and residual shrinkage.
The prior art methods have an additional drawback in that, because of the particular manner in which the continuous filament is supplied, the filament must necessarily be a meltspinning type and the choice of materials for the filament is quite limited.